Facile synthesis of TiO2/Chitosan nanohybrid for adsorption-assisted rapid photodegradation of an azo dye in water

A series of bifunctional nanohybrids containing different proportions of chitosan and titanium dioxide (TiO2) were prepared through precipitation technique and applied for removal of a model anionic azo dye, Remazol Orange 3R (RO), from aqueous solution. This study reveals the dual benefit of adsorption and photocatalytic degradation of RO by TiO2/Chitosan nanohybrids. Nanohybrid fabricated from 80% TiO2 (w/w) and 20% chitosan (w/w) termed as T0.80CS0.20 removed ∼98.8% RO within only 8 min at pH 2.0 under sunlight irradiation from 60 mg L−1 dye solution. This was mainly due to the simultaneous role of adsorption and photodegradation activities of nanohybrids. The adsorption performance of T0.80CS0.20 was investigated in terms of the Langmuir isotherm under dark and the maximum adsorption capacity of T0.80CS0.20 for RO was found to be 243.9 mg g−1. Electrostatic interaction was suggested as a plausible mechanism for RO adsorption whereas photogenerated holes controlled photocatalytic degradation of RO by producing sufficient quantities of different radical species. In addition, T0.80CS0.20 can be regenerated for removal of RO by simple alkali washing. Therefore, T0.80CS0.20 is recommended as a promising photocatalyst for the removal of RO dye from water.